its a combo of the dwell setting hpr and lpr that will reflect velocity. on a bone stock non broken in marker that may be true but a higher hpr isnt a problem unless you start blowing out the tophat orings....then the hpr is too high.

It'll also depend on how the paint fits in your barrel. If you're massively overboring then you're wasting air and will need to increase pressure/dwell to get up to velocity. I guess that would also be true for very extreme underboring, but at that point I'd be more worried about the paint busting in the barrel if there's enough drag to slow the ball down rather than create a tight seal and help it accelerate better, which underboring usually results in. Considering the stock PM8 barrel is a .690, and how small paint is now (I've had paint roll through a .679 insert)... that's very likely an issue you're experiencing.

It'll also depend on how the paint fits in your barrel. If you're massively overboring then you're wasting air and will need to increase pressure/dwell to get up to velocity. I guess that would also be true for very extreme underboring, but at that point I'd be more worried about the paint busting in the barrel if there's enough drag to slow the ball down rather than create a tight seal and help it accelerate better, which underboring usually results in. Considering the stock PM8 barrel is a .690, and how small paint is now (I've had paint roll through a .679 insert)... that's very likely an issue you're experiencing.